A power tool should be designed to satisfy a user's different requirements. In many working conditions, it is desired that the power tool has a rotatable working head to deal with different shaped objects and all the surfaces of an object. The type of power tool may vary, and include garden tools, cleaning tools, etc.
Take the case of garden tools, a hedge trimmer is a commonly used garden tool, which is used to trim bushes or hedges to maintain a beautiful shape. When trimming tall branches, people usually use a hedge trimmer with an extension pole. Compared with an ordinary hedge trimmer, the user does not need a ladder to trim the side surfaces of the tall braches if the user is using the extension hedge trimmer. However, when trimming the top and bottom of the tall trees, the user has to climb to the top of the ladder and bend over to view the bottom of the tree, which is difficult and troublesome. For solving the problem, an extension hedge trimmer with a rotatable working head is designed in the prior art. U.S. Patent Application Publication No. 2007/0000138 discloses this kind of hedge trimmer. A power head of the hedge trimmer comprises a stator cartridge. A head support rotates about the stator cartridge and is engaged by way of a movable engagement pin that is received within a selected recess defined in the stator cartridge. When a user needs to adjust the angular position of the power head, the user must hold a latch in the disengagement position using one hand, and rotate the power head using another hand. After the power head is rotated to the desired angular position relative to the head support and a handle, the latch is released to lock the power head at the angular position.
The hedge trimmer described above solves the problems with trimming the top and bottom of tall trees, but it also has disadvantages. For example, the angle adjusting structure is complicated and has an increased manufacture cost. In addition, the adjusting method is inconvenient. During the adjusting operation, the user moves and holds the latch in the disengagement position while rotating the power head to adjust its angular position. The power head comprises a motor and a transmission therein, so the weight of the power head may make it difficult if the user is rotating the power head with only one hand.